Traditionally torpedoes, such as MK-48 and MK-46 designs, are designed to destroy adversary aquatic vessels which may be surface vessels or submarine vessels. Typically, torpedoes do not have programming capabilities and most torpedoes do not utilize electric batteries because battery power diminishes over time. Torpedoes typically use a gas engine and compressed air to provide the power after the torpedo is loaded and launched by a submarine crew. These torpedoes are mainly launched from a launching tube with a complicated compressed air manifold system. The procedure to load and launch a torpedo is time consuming, requires careful operation by the crew, and is dangerous. The storage and launch system for a torpedo requires a large amount of precious high pressure waterproof space of a manned submarine, and the refill of multiple torpedoes takes a long time.
There are typically six steps to launch a torpedo. In step 1, with an outer door closed, an inner door is opened and a torpedo is loaded into a launch tube. The launch tube may be high pressure waterproof with complicated manifold water and pneumatic pipes. The inner door is then closed. In step 2, water pressure prevents the outer door from opening. To offset this pressure, the launch tube may be flooded from a shipboard tank, then a valve to the sea may open to equalize the pressure. The displaced air is vented inboard. In step 3, the outer door may be opened and the torpedo is ready to fire. In step 4, compressed air ejects the torpedo. The air is vented inboard so that air pockets or bubbles cannot rise to the surface and reveal the position of the vessel. In step 5, the compressed air may be shut off and the launch tube fills with seawater. This offsets the lost weight of the torpedo and keeps the vessel in trim. In step 6, the outer door is closed and the launch tube drains to a drain tank. The inner door may now be opened and the launch tube reloaded.
Traditionally, when a torpedo is launched, exhaust and pneumatic noise may be generated due to the gas engine. An adversary ship may detect these noises and launch counter measure devices to confuse the torpedo.
A typical unmanned underwater vehicle does not have the capabilities to store a large number of torpedoes and does not have a torpedo launch system. A modern manned submarine such as a German Type-214 design or a Japan Soryu design is approximately 4,000 tons, stores 24 to 30 torpedoes, requires about 65 crew members and officers and costs approximately $400 million. In contrast, a J-type Underwater Vehicle (JUV) such as a JUV-700, is approximately 100 tons, stores 40 torpedoes, requires six crew members or unmanned operation and costs approximately $30 million.